The earth itself comprises a biosphere in which microorganisms, plants, and animals, including humans, exist in a more or less steady state, wherein matter is a finite resource which is continually recycled. There is continual energy input in the form of solar radiation. The quantity of matter gained or lost to space outside the earth's atmosphere is minute. Thus, the earth is a closed ecological system which may be referred to herein as Biosphere I. Although the earth recycles matter continually between the soil, oceans, atmosphere, biomass, and the like, in a nearly steady state, there appears to be a drift of conditions as indicated by increasing carbon dioxide concentration in the atmosphere, the well-known "ozone hole," and other effects which may not have been detected as yet.
It is desirable to provide a microcosm of the biosphere known as earth for study of the interaction of components, and development of techniques for influencing our environment. Such experiments are difficult at best in the open system provided on earth, where matter is exchanged between the earth's environment and the experiment itself. It is, therefore, desirable to provide a system that is completely enclosed so that no matter is exchanged with the earth's environment. It is desirable to have humans within this miniaturized biosphere to provide control, and conduct scientific research within a closed system where conditions may be varied as desired.
Being a closed system having humans within the system requires that they be provided with a habitable atmosphere and a balanced diet for long-term health and that closed cycles be established for carbon, oxygen, nitrogen, other nutrients, water, and the like, so that the closed system may remain in a more or less steady state for the long periods of time required for conducting meaningful scientific research.
There is, therefore, being established near Oracle, Arizona, a completely closed ecological system referred to as Biosphere 2. The system completely encloses about one hectare of land and 175,000 cubic meters of space isolated from the earth's environment by an impermeable skin so that no matter is transferred. The above ground portion of the skin is largely transparent for receiving solar radiation. Electrical energy is provided to the closed system, and heat may be transferred to or from the system as required. Thus, the Biosphere 2 closed ecological system is closed as to matter, but open as to energy. For meaningful research, it also remains open for transfer of information.
The Biosphere 2 system provides facilities for occupation by eight humans who can remain sealed in the system under healthful living conditions for two years or more. Diverse plant, animal and microorganism populations in the system assure balancing of the ecology for long periods.
In Biosphere I, namely the earth, the interactions of and immense diversity of life species and chemical and physical reactions are such that a relatively steady state prevails without human intervention (if anything, humans tend to disrupt the steady state). In a smaller closed ecological system, however, it is improbable that a habitable environment would prevail for very long without human intervention.
For example, the atmosphere within the closed system could drift far from the composition usual in outside air, or could accumulate toxic vapors which could be harmful to the inhabitants. Thus, it is desirable to provide means for controlling the cycles of matter in the closed ecological system and to do that one needs to know what is happening in the atmosphere for detecting trends toward imbalance so that remedial steps may be taken before the undesirable condition becomes extreme. Furthermore, knowledge of the composition of the atmosphere is important data for evaluating experiments conducted within the closed system.
Biosphere 2 has a number of biomes within the closed system. There is, for example, a human habitat which serves as a residence and workplace for the people occupying the system. This is adjacent to an agricultural area which provides the principal food supply for the occupants. This is connected to a so-called wilderness area which has different ecological niches varying from a humid rain forest at one end to a desert at the other end. The organisms in these various areas within Biosphere 2 are continually exchanging various gases with the atmosphere within the closed system. Some plants may, for example, emit organic vapors as well as take up carbon dioxide and release oxygen during photosynthesis.
Since conditions may vary considerably from biome to biome, it is desirable to sample the air in various locations throughout Biosphere 2 for analysis. Trace quantities of some gases are of interest and precision instruments are therefore needed. To provided these costly instruments in each biome would b prohibitively expensive. Furthermore, to compare the analyses of gases between various biomes for subtle gradients, continual calibration of the various instruments would be required. For such reasons, it is desirable to employ precision instruments maintained in a single analytical laboratory. This introduces a requirement for gathering samples from remote locations and conveying them to the analytical laboratory. One could, of course, employ portable gas sampling bottles, but the required labor would be extraordinary for the regular monitoring that it desired. A remote sampling system is, therefore, desirable.
As with any sampling system it is important that the air sample delivered to the analysis instruments should be representative of the air at the remote location. It is desirable that the sampling system be arranged so that the taking of samples and analysis may be automated and controlled by computer inputs. It is also desirable that means be provided for calibrating the system to assure that the analytical data are truly representative of the air being sampled.